The technology is already known of automating conventional starting clutches by hydraulic, pneumatic or electric motor powered actuators together with one of the actuator control circuits in such a way, that the formerly necessary, driver-operated clutch pedal can be eliminated. In such a case, the control circuitry is provided with speed of rotation sensors, which determine the rotary speed of an internal combustion motor and/or the rotary speed of input to a starting clutch in the following drive string. It is possible that a control circuit can so regulate the actuator, that the starting clutch engages itself with minimal kickback, this being dependent, respectively, upon the speed of rotation of the motor and that of the input to the transmission. Dependency may also lie on other operational parameters determined by appropriate sensors. In order to avoid flooding an internal combustion motor upon stopping, the starting clutch is controlled to go into a complete state of non-engagement as soon as the speed of rotation of the motor drops below a predetermined speed of rotation-threshold, which is less than that of the idling speed of the motor.
As a rule, a motor vehicle sets itself in motion in that the torque of the secondary sided clutch incrementally approaches the torque of the driving motor. If the resistance to movement is such that the vehicle, without the input of drive-torque, sets itself in motion, there exists a development of an unacceptably high speed of rotation for the clutch disk. Accordingly, for the prevention of an uncontrolled acceleration, the necessity arises of shutting down the vehicle by closing the clutch.
The aforesaid situation of the rolling-start, that is to say, an external starting of a vehicle, can be carried out in a given gear, even if the rolling start equipment situation is appropriate or inappropriate. For example, if the direction of rolling is contrary to that called for by the gearsetting, then the clutch engagement for the shutting down of the vehicle, dependent upon the kinetic energy thereof, leads either to a reversal of the direction of travel of the vehicle or to a reduction of the speed of rotation of the motor. In an extreme case, this can even bring about a reversal of the direction of rotation of the motor.
Conventionally, it is necessary for a motor vehicle starting gear train to function in an orderly way so that the motor vehicle moves itself in a direction defined by a current gearsetting in the transmission, particularly if false reactions of the clutch control circuit which regulates clutch closure are to be avoided. In other words, the motor vehicle should only move forwards, if one of the forward travel gears is engaged, and likewise, should only move backwards, if the reverse gear has been set. If a motor vehicle moves itself forward, for example, by externally applied rolling on a road incline, but is set in a reverse gear, then, dependent upon the type of control arrangement, the possibility is, that in this situation, in spite of an effort of the driver to start, the clutch of the vehicle cannot be engaged or else, without any starting effort, the clutch fully engages itself and thereby the motor is flooded.
DE 199 32 052 A1 discloses a process for the detection of the direction of rotation of an output shaft of an automatic transmission, when a motor vehicle rolls. In this case, an operating parameter, which involves a time lapse, is determined and compared with the actual values for the existing state of travel. In short, gear change synchronization is computed and compared with the true travel condition.
A disadvantage of this process is to be found therein, in that actual input values can vary in accordance with the type of motor vehicle. It is also possible that the computational values can be dependent upon the state of the vehicle at the time of determination. Thus, it is necessary, that the values must be selected with respect to the type of vehicle and, in a worst-case situation, in connection with the loading carried by the vehicle. This requires an excessive need for computer memory. Further, it is of disadvantage that the computations for gear mesh synchronicity are time-intensive, which can lead to delayed shifting operations. Accordingly, to carry out this process demands much design work, which is necessarily accompanied by relatively high cost.
The purpose of the invention is to introduce a procedure with which in a simple manner, the directions of rotation of the input and output components of a starting clutch are individually detected, both from the standpoint of a faulty reaction of the automatic activation of the starting clutch, and that inordinate vehicle motion can be prevented, when the selected transmission gear does not match the direction of travel of the vehicle. According to the invention, the use of a separate direction-determining sensor can be dispensed with.
The vehicle transmission gear train will be altered with the installation of a starting clutch responsive to an actuator, that is to say, the starting clutch is to operate on a centrifugal force basis.